This invention relates to the art of fabric softening, and more particularly, it relates to a substantially translucent, highly concentrated, stable fabric softening composition useful in the wash or rinse cycle of an automatic washing machine and a process for forming said formulation.
The art of fabric softening is an old one and generally most of the fabric softeners which have been heretofore formulated and marketed required addition to the rinse cycle of a washing machine. By and large, these formulations were aqueous dispersions containing active ingredients in concentrations from 4 to 7%. In recent years formulations have been developed which allowed the consumer to add the softening formulation before the wash cycle along with the detergent and bleach. However, many problems were experienced with such softening formulations.
Because the ideal pre-wash cycle fabric softener would have to be in sufficient quantity to remain active through the wash cycle in order to be effective during the rinse cycle, two types of approaches were taken to achieve this end. Initially, compositions having a relatively low concentration of active ingredients were added in large amounts at the beginning of the wash cycle. This procedure presented many problems. It was necessary for the consumer to employ on the order of at least twice the normal amount of formulation required. This procedure would also require that the consumer maintain large quantities of fabric softening formulations on his shelves and would involve wasteful use of fabric softeners. Therefore, consumers were reluctant to employ such fabric softening formulations.
To overcome this difficulty, it has been proposed to prepare a high potency fabric softening formulation which, when employed in conventional quantities, would provide effective fabric softening in the presence of detergents in the wash cycle of laundry machines. For this purpose fabric softening formulations containing in the order of 10 to 12% active ingredients were proposed. However, it has not been feasible heretofore to prepare emulsions of a high concentration employing the commercially accepted fabric softeners available. The generally effective fabric softeners which have found wide spread commercial acceptance, such as the di-(higher alkyl)-di-(lower alkyl) ammonium salts, could not be readily processed into stable, highly concentrated emulsions. Using typically commercially available fabric softening agents, formulations containing a maximum of 7 to 8% actives can be prepared without incurring stability difficulties.
Previous attempts to prepare more highly concentrated fabric softening formulations have been subject to numerous defects and deficiencies. For example, in U.S. Pat. No. 3,681,241 it has been proposed to employ a fabric softening composition which includes a quaternary ammonium compound, at least one amido imidazolinium alkyl sulfate and an ionizable salt in amounts between 0.005% and 0.1% for viscosity control. It has further been proposed that the subject softening emulsion have a viscosity in the order of 200 to 500 centipoises for optimum consumer acceptance. It has also been proposed that the composition be homogenized at pressures up to about 2500 lbs. per square inch. Various defects have been noted with such proposed highly concentrated emulsions. Initially, it has been found that unless supplementary emulsions stabilizers, such as conventional surfactants are employed, then within three to four days after preparation, the emulsions tend to stratify and unduly increase in viscosity beyond an amount acceptable to the consumer.
Such concentrated softening compositions as disclosed in the U.S. Pat. No. 3,681,241 patent are opaque, not transluscent. It has long been recognized that consumer acceptability is highly enhanced if a translucent composition is formulated for commercial use. Consumers can establish the purity of the softening composition by changes in the opacity of a composition should the composition be marketed in a translucent state. This is not possible with the opaque compositions.
Further, in the proposed preparations which are allegedly storage stable it is necessary to employ not only a mixture of quaternary fabric softening agents, but also non-ionic stabilizers and electrolytes for viscosity control. This need has unduly increased the cost of manufacturing the product and has required more extensive mixing equipment and inventories of raw materials. The prior art proposed concentrated softeners have initial viscosities in excess of 200 centipoises. However, it has long been recognized that homemakers prefer to employ liquid laundry compositions which are easy to pour and are readily exhausted from the container. Accordingly, it has long been considered desirable to provide liquified laundry aids in forms having viscosity less than at least 150 centipoises and preferably less than 100 centipoises. Further, laundry product manufacturers have long desired a low cost and highly concentrated fabric softener which, owing to its low viscosity and other factors, is readily diluted during the wash cycle and exhibits excellent exhaustion properties onto synthetic and natural fibers.
Accordingly, there exists a long felt need, which up to now has been unsatisfied, to provide a highly concentrated, storage stable substantially translucent fabric softening formulation having a low viscosity and effective softening and exhaustion properties.
It is, therefore, a primary object of the invention to provide a highly concentrated fabric softening composition having from about 7 to 15% and particularly 10 to 14% active fabric softening ingredients having extended storage stability.
It is another object of the invention to provide a storage-stable concentrated fabric softening composition exhibiting low viscosity for enhanced pouring capabilities.
It is an additional object to provide a stable, highly concentrated fabric softener having a single active ingredient to reduce manufacturing and consumer costs.
It is yet another object to provide a substantially translucent, highly concentrated, storage-stable fabric softening formulation.
Other objects and advantages will be apparent to those skilled in the view of the following detailed description of the invention.